Katharina S Rufener1, Mathias S Oechslin2, Tino Zaehle3, Martin Meyer4. 1. Department of Neurology, Otto-von-Guericke University, Magdeburg, Germany; Research Unit for Neuroplasticity and Learning of the Healthy Aging Brain, University of Zurich, Switzerland. Electronic address: katharina.rufener@med.ovgu.de. 2. International Normal Aging and Plasticity Imaging Center, Zurich, Switzerland. 3. Department of Neurology, Otto-von-Guericke University, Magdeburg, Germany. 4. Research Unit for Neuroplasticity and Learning of the Healthy Aging Brain, University of Zurich, Switzerland; International Normal Aging and Plasticity Imaging Center, Zurich, Switzerland; University Research Priority Program "Dynamics of Healthy Aging", University of Zurich, Switzerland; Cognitive Psychology Unit (CPU), University of Klagenfurt, Klagenfurt am Wörthersee, Austria.
Abstract
BACKGROUND: Normal aging is accompanied by a functional decline in processing temporal features of spoken language, such as voice onset time (VOT). On an electrophysiological level, this finding is paralleled by altered patterns of gamma oscillations. OBJECTIVE: Using 40 Hz transcranial alternating current stimulation (tACS) over the bilateral auditory cortex, this study aims to compare the effect of tACS to modulate VOT-processing in samples of healthy young and older adults. METHODS: Twenty-five healthy young (age 20-35 years) and 20 older adults (age 60-75 years) participated in this study. Presented with an auditory phoneme categorization task participants received 40 Hz and 6 Hz tACS on two consecutive sessions. RESULTS: While 40 Hz tACS diminished task accuracy in young adults, older adults benefitted from this stimulation resulting in a more precise phonetic categorization. CONCLUSION: The results of the study are discussed with respect to the non-linear relationship between gamma oscillations in the vicinity of the auditory cortex and VOT-processing. The present findings are promising in the context of an intervention for subjects with impaired ability to process temporal acoustic features in the speech signal.
BACKGROUND: Normal aging is accompanied by a functional decline in processing temporal features of spoken language, such as voice onset time (VOT). On an electrophysiological level, this finding is paralleled by altered patterns of gamma oscillations. OBJECTIVE: Using 40 Hz transcranial alternating current stimulation (tACS) over the bilateral auditory cortex, this study aims to compare the effect of tACS to modulate VOT-processing in samples of healthy young and older adults. METHODS: Twenty-five healthy young (age 20-35 years) and 20 older adults (age 60-75 years) participated in this study. Presented with an auditory phoneme categorization task participants received 40 Hz and 6 Hz tACS on two consecutive sessions. RESULTS: While 40 Hz tACS diminished task accuracy in young adults, older adults benefitted from this stimulation resulting in a more precise phonetic categorization. CONCLUSION: The results of the study are discussed with respect to the non-linear relationship between gamma oscillations in the vicinity of the auditory cortex and VOT-processing. The present findings are promising in the context of an intervention for subjects with impaired ability to process temporal acoustic features in the speech signal.
Authors: Basil C Preisig; Lars Riecke; Matthias J Sjerps; Anne Kösem; Benjamin R Kop; Bob Bramson; Peter Hagoort; Alexis Hervais-Adelman Journal: Proc Natl Acad Sci U S A Date: 2021-02-16 Impact factor: 11.205